Fluid-pressure tool



y E. PENBERTHY 1,769,036

FLUID PRESSURE r001.

Filed Jan. 2%, 1925 BYL; ATTO/P/Vf) Patented July 1," 1930 i PATENT .IOE

ERNEST PENBEBTI-IY, F DETROIT; MICHIGAN, .ASSIGNOR TO CHICAGO ,PNEUMATIG TOOL COMPANYQ'OF NEW YORK, N. Y., CORPORATION OF NEW JERSEY FLUID-PRESSURE TOOL Application filed January 27, 1925. Serial. No. 5,004.

This invention relates to fluid pressure percussion tools of the typeused' in mining, quarrying and slmilar operations.

result in a tool characterized by high piston speed and penetrating power, and in general to improve prior construction in the interest of more eflicient and satisfactory operation With these and other objects in view the invention is illustrated in the accompanying 20. drawings in what is now considered to be its preferred form. In the drawings, Fig. 1 isa longitudinal sectionalview of so much of a drill as is necessary to illustrate the invention; and Fig. 2 is a similar view but 25. partly cut away showing the operative parts of the drill in a difierent position.

The embodiment of the invention chosen for the purpose of illustration comprises a stoping drill having a cylinder 3 to which an air feed cylinder 4 is attached. Within the drill cylinder 3 is mounted for reciprocatory movement a two diameter piston5 consisting of a head 5 fitting the large bore 3 of the piston chamber and with a reduced stem 5 extending rearwardly therefrom and fitting the small bore 3 of the piston chamber. The blows of the percussive member or piston 5 are imparted to the drill bit or steel 6 supported in the usual manner in a front head or chuck either directly or through an anvil 8 slidably mounted in a bushing or guide member 9 interposed betglween the front head 7 and the drill cyliner 3. a

The motive fluid for actuating both the air feed and the percussive piston 5 is admitted through the usual throttle valve 10. The motive fluid for the percussive -motor enters directly into a chamber 11 which com-- 0. municates directly with the small bore 3? of In par ticular it relates to tools of this type espethe piston chamber so that the end ofthe piston stem 5 is continuously subjected to the pressure of the live motive fluid and serves as a constant pressure area for urging the piston in a forward direction. The other pressure areas of thepisto'n comprising the front and rear faces of the head 5 are intermittently supplied with motive fluid under control of an automatically actuated valve 12. This valve is mounted for reciprocatory movement in a valve chamber 13. Valve 12 is of the spool type having end heads 12 and 12 of equal diameter connected by a reduced neck 12. Motive fluid reaches the valve through a passage 14 connecting directly with the chamber 11 and by a second passage 15 which communicates with a groove 15 in the small; bore 3" of the piston chamber.

controlled, motive fluid fromchamber 11 havingaccess thereto only when the rear end of the stem 5 on its forward movement uncovers the groove15 Passages 14 and 15 terminate in grooves 14 and 15 adjacent the rear or right hand end or head 12 of the valve in position to be controlled thereby; thus when the valve is in its rearward position (Fig. 1) motive fluid from passage 14. passes around the neck of the valve 12 to a passage 16 terminating in a groove 16? at the rear of the large bore '8 of the piston chamber; when the valve moves toits forward position (F ig; 2) connection is broken between the passages 14 and 16 by the head 12 of the valvebut established between passage 15 and a passage 17 extending from the rear end of the valvev to the front end of the piston bore 3* to effect the return stroke of the piston. The front head 12 of the valve controls an exhaust port 18 which is uncovered in the forward position of they valve (Fig. 2) and placed in communication with passage 16 thus serving as an auxiliary exhaust for the rear face of the piston head 5*, the main exhaust 18being piston controlled and alternately connected by the lat- Thus passage 15 is piston ter in its reciprocations with the piston;

chamber before and'behind piston head 5.

To accomplish the shift-ing of the valve in timed relation with the movements'of the piston the valve head 12 has two restricted ports 20 and 21 within the limits of the live air groove 14- in both positions of the valve,

the one communicating with an axial bore 20 within the valve extending to the front.

limited amount, that which enters port 20 and passes through bore 20 to the front end of the valve being vented to the piston chamher in certain positions of the piston by a vent passage 23 while that which passes through port 21 to the rear end of the valve has access to the piston. chamber through the piston return passa of a restricted fluid supply to the ends of the valve vented through the valve chamber together with the piston controlled main exhaust provides for the shifting" of the valve at precisely the right instant.

The operation of the drill is as follows: lVith the parts in the position shown in Fig. 1 motive fluid admitted by the throttle valve 10 to the chamber 11 has access directly to the end of the piston stem 5 and through passage 14-, valve chamber 13 and passage 16 to the rear face of piston head 5 thus driving the latter on its forward or working stroke. The piston return passage 17 communicating with the rear end of the valve is open to exhaust'through the piston chamher 3 and main exhaust 19. As the'piston advances the stem 5 uncovers the groove 15 admitting motive fluid'from chamber 11 to this pressure being increased by the live motive fluid admitted in limited amount through port 21. J ustas the piston deli'vers its blow, head 5 passes beyond exhaust port 19 and throws the rearward end of piston bore 3 open to exhaust 2). The pressure heretofore obtaining in vent passage 23 immediately falls and the valve shifts to the position shown in Fig. 2. Immediately. the motive fluid heretofore trapped in passage 15 by head 12 of the valve pours into passage 17 and reaches the front face of piston head 5 in time to catch the piss ton as it rebounds and to effect its rearward stroke. At the'same valve shifting instant communication between passage 16 and the live air passage 14 is cut off by head 12 but the auxiliary exhaust port 18 is uncovered by head 12". This permits the escape of any air trapped by the piston head 5 in ge 17. This combination the rear end of bore 3 after it closes main exhaust 19, thus avoiding back pressure and contributing to a full rearward stroke of the piston. The stem 5 of the piston closes groove 15 just before the head 5 of the piston opens the front end of the piston chamber to the main exhaust 19, the rearward movement of the piston then being continued until exhaust 19 is fully opened by the expansion ofthe motive fluid in the passage 17 augmented by the limited amount of motive fluid entering through port 21. The momentum acquired by the piston carries it against the constant pressure on the end of thestem o well beyond the main exhaust 19 whereupon the closing of the vent passage 23 by piston head 5 causes the motive fluid admitted by port 20 to build up quickly against the head 12 of the valve and shift the latter, since the fluid pressure passing across head 12 from passage 15 is vented to atmosphere through port 19 and offers no substantial resistance to the movement of the valve.

To prevent leakage of motive fluid along the piston stem 5" between the groove 15 and the end of bore 3 when the piston is on its rearward stroke, which leakage would interfere with the full rearward stroke of the piston, a groove 24 is provided to intercept such leakage, this groove having a connection 25 to atmosphere.

I claim as my invention:

1. In combination in a fluid pressure percussive tool having a cylinder with a two diameter bore. a two diameter hammer piston fitting said cylinder bore, said piston having two pressure areas for driving it in one direction and a single pressure area for returning it, one of said first-named areas being continuously subjected to the motive fluid and the two remaining areas being intermittently subjected to the motive fluid, motive fluid supply passages extending to said intermittent areas, one of said passages being controlled by said piston and the other independent of piston control, and a valve controlling both said passages.

2. In a fluid pressure percussive tool, in combinatioma reciprocatory piston having two pressure areas for driving it in one direction and a single area for returning it. means subjecting one of said first named areas continuously to motive fluid, and

. means subjecting the two remaining areas to intermittent pressure comprising passages extending to said areas, the one being inclependent of said piston and the other under control of said pistoma valve controlling both said passages, said valve also controlling an auxiliary exhaust for one of said areas.

3. In a fluid pressure percussive tool, in combinatioma reciprocatory piston having two pressure areas for driving it in one 9 0 i e. f 31- direction and a single area for returning it, means subjecting one of said first, named areas continuously to motive fluid, and means subjecting the two remaining areas to intermittent pressure comprising passages extending to said areas, theone being independentoi' said piston and the other under control of said piston, a valve controlling both said passages, and means including connections from said independent supply passageto opposed pressure areas of the valve for etfectingshifting of the valve in timed relation with the movements of said".

piston.

4:. In control mechanism for a fluidpressure tool having a two diameter piston with two small pressure areas for driving it forwardly and one large pressure area for returning it, a valveof the spool type having end heads of equal diameter connected by a reduced necln'two live air passages terminat ing adjacent one valve head, one of said passages being controlled by said piston, means continuously passing motive fluid in limited amount from theother live air passage to the ends of the valve to shift the latter, vent passages extending from both ends of the valve to the piston chamber, the vent from one end serving as the supply passage for the return stroke of the piston, thereby to eifect the shifting of the valve in one direction by limited live air augmentedby air compressed by the piston andjforced into said return passage near the end of its forward stroke, thereupon to admit motive fluid in substantial amount from said piston controlled passage to said return passage to ef feet. the return or. non-working'stroke of the piston. V I

5. In control mechanism for fluid pressure percussive tools of the type having a cylinder and a piston reciprocable therein,-in combination, a valve having a pressure area for shifting the same, a passage extending from said area to the piston chamber to admit pressure fluid thereto to drive the piston in one direction, a piston controlled passage extending to said valve for connection with said first named passage on shifting of the valve for admitting live air to said first named passage and means continuously admitting live air in-limited amount to said area to assist in effecting both the shifting of the valve and the movement of the piston.

6. In valve mechanism for fluid pressure percussive tools ,ofthe type having a cylinder anda percussive member reciprocable therein, in combination, a spool valve having endheads of equal diameter and a reduced connecting portion, means continuously passing motive fluid in limited amount to both ends of the valve, means comprising ports and passages under control of oneof said heads for directing the motive fluid in altercussive member.

Y A 1 I 1 7; In valve mechanlsm forfluid pressure nation to opposedpressure areas on the perpercussivle tools of the type having acylinder j and a percussivememberreciprocable therein, in combination, a.- spool valve having end he'ads of equal diameter and a reduced connecting portlon, means continuously passmg motivefluid in limited amount'to-both ends of the valve, means comprisingports and passages'controlled by oneof said heads I fOr-directing motive fluid in alternation to opposedpressure areas on the, percussive member, and the other valve head control ling anexhaust port: for one of said areas? 8. In valve mechanism for fluid pressure percussive tools of the type having a cylinder and a percussive member reciprocable therein, in combination, a spool valve hav ingend heads of equal diameter and a re duced connectingport-ion, ports and. .pas-

sages controlled by said valve extending to I opposed pressure areas-in the percussing member, independent passages extending to the valve chamber for conducting motive fluid thereto, one head of said valve con trolling in alternation the admission of'motive fluid from said second'named passages to said first named passages, one 01": said motive fluid passages being independent of said percussive member and the other mo-' tive fluid passage being controlled by said percussive member.

9. In valve mechanism for fluid pressure percussive tools of the type having a cylinder and a percussive member reciprocable thereimin' combination, a spool valve having end heads of equal diameter and a reduced connecting portion, ports andpasfsages controlled by said valve extending to opposed pressure areas of the precussing,

member, separate passages extending to the valve chamber for conducting motive fluid thereto, one head of said valve controlling in alternation the admission of motive fluid from said second named passages tosaid first named passages, one of said motive fluid passages being independent of said'percussive member and the other motivefluid passage being controlled by i said} percussive member, and means including the continuous admission of motive fluid in. limited amount from said independent motive fluid passage to the ends of'said valve for effecting shifting of-the same in timed relation withthe movements of said piston.

10. In combination in a fluid pressure percussive tool having a cylinder with a two diameter bore, a two diameter hammer piston fitting said cylinder bore, said piston having two pressure areas for driving it in i one direction and a single pressurearea' for returning it, one of said first named areas being continuously subjected to motive fluid and the remaining areas being intermittently subjected -to motive fluid, amotive fluid supply passage extending to each of saidvintermittent areas, one of said motive fluidpassages being controlled by said piston and the other independent of piston control, and an automatically thrown valve for controlling both said motive fluid supply passages. 11. In combination in a fluid pressure percussive tool having a cylinder with a two diameter bore, a two diameter hammer pistonpfitting said cylinder bore, said piston having two pressure areas for driving it in one direction and a single ressure area for returning it, one of said rst named areas being continuously subjected to motive fluid and the remaining areas being intermittently subjected to motive fluid, :motive fluid supply passages extending to said intermittent areas, one of said passages being controlled by said piston and the other independent of piston control, a valve control- :ling both said passages, and means interme diate said piston controlled passages and the large bore of said piston for preventing leakage of motive fluid from said constant pressure area to ,one of said intermittent areas. .l

Signed by me at Detroit, Mich, this 28rd day of J anuary,'1925.

ERNEST PENBERTHY. 

